1. Field of the Invention
This invention is related to a reversible accumulator conveyor having start-up action after the articles being conveyed have come to rest.
2. Description of the Prior Art
Accmulating conveyors as a conveyor entity became widely known to the material handling field in the late 1950's. Before that time, various types of live roller conveyors adjusted to their minimum pressure, served this function.
There are two types of accumulating conveyors on the market today. The first is of a release drive type. In principal, they operate as follows: an article is stopped on the conveyor at a trigger point. The trigger activates a linkage mechanism which removes the driving force, usually a conveyor belt or chain, from a segment of the conveyor behind the stalled article. This results in the next article stopping when this dead area is reached. A trigger mechanism located within the dead area is engaged by the second article causing a like segment behind it to lose its driving force. This process repeats itself along the entire length of the accumulating conveyor. Back pressure is usually limited to the driving force on the first article. Some of the disadvantages of the release drive type conveyors are that they operate in only one direction; articles must be heavy enough to trip the trigger; the linkage is subject to environment causing it to malfunction, and there is a limited range between lightest and heaviest articles to be conveyed.
U.S. Pat. No. 3,416,642 by Muller is a modification of the release drive type concept. In lieu of a trigger to be activated by the article this patent employs a floating center mechanism. The effect on the second and subsequent articles is the same as above.
The second type of accumulating conveyor is the "minimum pressure" type. This method has been around for over 35 years. The more recent application of this principal came about as new drive belts were developed with a low co-efficient of friction. Some have employed mechanical means to accomplish the same feat. Conveyors of this design are usually advertised with back pressures under 4%.
The essence of the minimum pressure type conveyor is to have the drive pressure low enough so as not to damage the first article from the back pressure of the second and subsequent articles, yet strong enough to drive each article when released to convey. Some of the disadvantages of this type of conveyor are that they have a limited range between light and heavy articles to be conveyed; and the length of the conveyor is limited due to linear pressure build up. U.S. Pat. No. 3,563,365 by Loberg is a minimum pressure conveyor using V-belts as the drive mechanism.
Therefore, what is needed and what has been invented by me is a reversible accumulating conveyor possessing none of the foregoing deficiencies.